Canva is one of the best design tools available online. You can easily design book covers, banners and graphics for your blog or social media networks.
Grammarly: (Free & Paid) is one of the best and most popular online grammar and spell checkers available. It can be used within its standalone app or with MS Office. It comes with plugins for most browsers, including Safari and Chrome. It is also available as an iOS app.
A word processor and project management tool that stays with you from that first, unformed idea all the way through to the final draft. Outline and structure your ideas, take notes, view research alongside your writing and compose the constituent pieces of your text in isolation or in context.